Process of manufacturing brushes



April 3, 1928. 1,665,152

R. M. WITHYCOMBE PROCESS OF MANUFACTURING BRUSHES Filed Oct. 2. 1924 jwuewio z paratively long. I

cordlng to known processes has not been Patented Apr. 3, 1 928.

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iipucaubn tied October 2, 1924, SerialNo, 741,256, as in As ana; as 2,1524.

This'iiivention relates to a process f or making brushes and has for its objectia proc- 'ess for manufacturing that type of brushv which is composed of a strip of rubber cut into filaments for a portion of its width, the strip beingthe'n so aggregated as to bring closely together into a tuft.-

' Heretofore it has been found difficult to out filaments with any degree of-rapidity without distorting them, due totheextreme elasticity, with consequent mobility, of the rubber; A further disadvantage has been that the filaments, when gathered together, into a tuft, have sometimes tended to incline outwardly especially when the strip is very thin or the filaments are com- Furt-her, a brush made acwell adapted that use where' it is essential for the brush shall carry a considerable quantity of liquid, because in such brushes the filaments lie closelyadjacent to each other and substantially parallel so that there are no decided spaces orlinterstices between which the liquid may be retained. I have found, however, that if the filaments are formed with a curved set, the concave side'being directed inwardly, the fila- -ments will when the strip is formed into a shown in elevation.

brush be forced apart in an intermediate portion of the brush forming reservoirs which retain the liquid bysurface tension and deliver it to the'end of the brush in the usual manner by capillarity. V The process of the present invention concerns itself both with making the cutting of the filaments easy and with imparting to them a curved set which will enable the brush to fulfill the desired function of a reservoir.

In the draw1ngs: p a

v 'Figure 1 represents a brush made according to the process of the present invention,

Figure 2 is a plan view of'a portion of a v strip of'rubber illustrating the step of cutting thefilaments.

I Figure 3-is a perspective view of a portion of the rubber, strip illustrating the curved set.

According to the invention, I firstsecure the strip of rubber by means of an adhesive to a temporary base 'or backing 2 of card board or other suitable flexible but comparatively' inelastic material. This backing, with the strip of rubber fastened therethe complete process. in several ways, one of which is to coat one side of the strip with linseed oil or it's equiv upon is then passed in any uaabismana j nto operatlve relation with cutting means by which the slits 3 are formed in the rub;

her, said slits preferably including parallel;

portions and inclined portions 5 which in: I terse'ct the parallel portions thus dividing i of the filaments may; be produced in wany suitable mann r; the slits bein formed-"in a single operation or in successive steps as "may be preferred. The whole strip; when the s'trip of rubber into two strips formed j with interleaved filaments 6. The cutting Y I so cut, is removed from the backing 2 and i 7' pulled apart formingtwo strips of reduced width, the filaments ofeach'strip being substantially identical in size-and shape, said strips forming. the stock blank, suitable lengths of which are used for the making of a brush. Each. of saidstrips,.when rolled,

forms the brush portion which may then be mounted in a suitable handle, or the. un-v vents the filaments from exercisingv their 1 property of elasticity while being cut, so that they remain immobile under the cutting means thereby avoiding distortion. v f The'provision of acurvedset inat least thefilamentous part of the strip prior to forming it into a brush is-one of the steps in V This may be effected alent and leave it to dry. The linseed oil" in dryingshrinks, thus drawing the rubber into a'concave form as shown in Figure'3. This effect can also be produced by stretchf ingthe rubber upon a saddle-shaped form and coating itwith any suitable composition by means of which adifierential tension is Y produced'on opposite sides'of the strip. The

curved set may also be imparted to the strip by vulcanizing the rubber, prior to cutting the same, upon a suitable form in the manner in which the inner tubes of automobile tires are produced I When the strip having the curved set is rolled with the concave sides of the filaments directed inwardly thebrush as-zsumes the form shown in Figure l in which the ends of the filaments oppose each other,

causing the intermediate portion of the brush: to bulge as shown at 7 in Figure 1,thereby forming inter-filamentous spaces ofsubstantial capacity constituting reservoirs in Which the liquid is retained by surface tension. These reservoirs have the form of widened interstices converging toward the lower end of the brush. This permits liquid from the intermediate portion of the brushto be drawn to the end of the brush by "capillarity.

Patent, isze i VAlt-hough' Ihave hereoutlined What I136? lieve to be a 'practical'and efficient process Having described my' invention What I claim as new and desire to secure by Letters '1, The process of making afilamentous rubber blank which consists in uniting one entire face, of a strip of flexible'elastic rub-J bet to airelatively non-elastic backing, cutting said strip with slits hileit is united to said backing, forming filaments, and removing said backing. y I

making a rubber brush 2 The process of Which consists in causing a strip offiexible elastic rubber to adhere to a transversely curved relatively"non-elastic backing, treating saidstrip While in adherence with said backing, by the curvature of said backing,

to give it a-cur'ved set determined bTlIIg- 7 ing said backing Wlth the adhered rubber,

into operative relation With suitable cutting means to Sllll'illiii rubber Without distortion,

forming filaments, removing said backing and rolling the strip With the concaved' side directed inwardly tObIlIlg the elements together into va tuft having the points thereof directed toward the axis of said tuft.

In testimony whereof I have hereunto'set my hand.

{ROBERT Mouse WITH coMBn 

